Semi-automatic firearms are well known and are often characterized by a magazine well formed in the grip of the firearm which is adapted to receive a magazine containing multiple rounds of ammunition therein. These magazines are themselves further characterized by a magazine follower and spring assembly which urges the stacked ammunition, round by round, into the firearm, automatically feeding ammunition after the previous round has been fired and the case extracted or ejected.
As shown in FIG. 1, a known magazine follower 10 sits atop a biasing spring and is positioned within the magazine 12, directly under the first round fed into the magazine. The spring is placed between a floor plate 14 at the bottom of the magazine and the magazine follower, and provides the necessary biasing force to urge the ammunition into the firing chamber. As shown in FIG. 1, the magazine 12 is in its empty position, with the magazine follower 10 in its extreme unloaded position.
Magazine followers generally move downward into the magazine when the magazine is loaded with ammunition. This compresses the spring and provides maximum return force. The magazine follower is urged upward by the spring force as ammunition is unloaded or as the weapon is fired.
One of the characteristics of certain semi-automatic firearms is that the slide is designed to stay open in the fully retracted mode after firing the last round in the magazine. This indicates that the firearm is empty of ammunition, and it also allows an operator to visually inspect the firing chamber and barrel.
Typically, semi-automatic firearms also include a slide lever integral to the frame which protrudes into the top of the magazine far enough to engage the follower, but not so far that the bullet will contact the slide lever and thereby cause the firearm to malfunction. In this regard, the slide lever is designed to take advantage of the characteristic of a standard cased round of ammunition. FIG. 2 illustrates a known slide lever 16, including a biasing arm 18 as well as a post 20 that is integrally mated to the firearm frame to provide selective rotation of the slide lever 16.
A round of ammunition comprises a bullet which sits atop and is engaged by a case which typically contains a primer and a propellant. Moreover, the overall shape of the round typically involves a lessened diameter at the top of the bullet as compared to the diameter at the bullet case interface, resulting in a substantial taper to the overall profile of the round.
When viewed from above then the round of ammunition will sit atop the magazine follower and there will be a portion of the follower which is not overlain by the round of ammunition due to the taper of the bullet.
Gun designers have taken advantage of these characteristics such that the biasing arm 18 on the slide lever 16 will contact the lip 22 of the magazine follower 10 as the magazine follower 10 rises in the magazine 12. After the last round has been expended from the magazine 12, the continued contact between the lip 22 and the biasing arm 18 causes the slide lever 16 to be rotated about the post 20, displacing the biasing arm 18 and a catch 24 upwards. A corresponding notch is cut in the slide of the firearm such that when the slide lever 16 is biased upwards, the catch 24 will engaged the notch in the slide, thereby stopping its forward movement.
Most bullets have a profile, or ojive, which is small enough to have an adequate distance between the outer edge of the bullet and the edge of the follower to allow engagement of the lip 22 with the biasing arm 18. Indeed, as shown in FIG. 2, the biasing arm 18 includes a tapered distal end 26 to help ensure that the rounds loaded in the magazine 12 are not interfered with by the biasing arm 18. The profile of the bullet is not, however, controlled by any industry or government regulations or guidelines, therefore the introduction of a differing sized caliber round in a given magazine may cause operational interruptions, such as jamming of the loading and/or feeding action of the magazine. This concern exists, regardless of the caliber of bullet used, whenever larger sized rounds are housed within a magazine originally adapted for a smaller round.
While larger caliber rounds, particularly those with large ojives, may fit within a magazine originally designed for smaller calibers, problems therefore oftentimes exist. As alluded to previously, this is because while the round of ammunition may well fit in the magazine itself, the ojive of such a round may be too large to allow the bullet to clear the tapered end 26 of the biasing arm 18 on the slide lever 16. As a result, the slide lever 16 would be moved upward with every new feed of ammunition into the chamber, causing the gun to malfunction and lock open with each and every round.
In some cases the firearm manufacturers have responded by decreasing the inward extension, or length, of the biasing arm 18 on the slide lever 16 in order to accommodate bullet designs of having varying degrees of ojive. This has proven to be an unreliable alteration as the firearm may then malfunction by not consistently locking the slide in its open position after the last round, since the extension by the biasing arm 18 into the magazine well can be marginal and, in certain instances, will miss the lip of the magazine follower 10 completely.
Indeed, certain manufacturers have in fact warned their customers to carefully select an ammunition to insure that neither of the above failure scenarios are present.
Other manufacturers have addressed this problem by designing wider and longer magazines and associated followers to provide a larger surface against which the biasing arm may engage the follower. This mandates, however, a larger firearm frame which is objectionable to many consumers causing them not to buy the product. In addition it requires more material and increases the weight of the firearm and generally increases the cost of the finished firearm.
With the forgoing problems and concerns in mind, it is the general object of the present invention to provide a magazine follower and assembly such that the need for an oversized frame is obviated, while still permitting a single magazine to be used in conjunction with multiple ammunition calibers having bullets of various ojives.